Cloning and polypeptide analysis of the leading region in F plasmid DNA transfer.

A segment of the F plasmid DNA, located between the origin of transfer and the primary F replication region, is the first to enter the recipient cell during conjugation. PstI, SalI, and SmaI restriction endonuclease sites have been mapped within this leading region in conjugational DNA transfer and chimeric plasmids carrying overlapping fragments of the region have been constructed. Analyses of polypeptides of Mr 27,800, 23,100, 14,400, and 11,000 to be encoded by sequences within the leading region.